{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-19569","assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","state":"PUBLISHED","assignerShortName":"zephyr","dateReserved":"2026-08-11T19:13:49.614Z","datePublished":"2026-10-09T07:16:45.305Z","dateUpdated":"2026-10-09T17:55:18.376Z"},"containers":{"cna":{"providerMetadata":{"orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","shortName":"zephyr","dateUpdated":"2026-10-09T07:16:45.305Z"},"title":"Integer overflow in dynamic kernel object allocation allows user-mode threads to corrupt the kernel heap","descriptions":[{"lang":"en","value":"dynamic_object_create() in kernel/userspace/userspace.c computed the backing allocation for a dynamically allocated kernel object as obj_size_get(otype) + size, and for thread stack elements as STACK_ELEMENT_DATA_SIZE(size) (a round-up plus fixed overhead), without checking either expression for unsigned wrap-around. A size close to SIZE_MAX makes the computed total wrap to a very small value, so the heap chunk handed out is a few bytes while the object descriptor is still tagged with the full requested type and registered in the kernel object table.\n\nThe size argument reaches that arithmetic directly from user mode. k_object_alloc_size() is declared __syscall in include/zephyr/sys/kobject.h, its verifier z_vrfy_k_object_alloc_size() in kernel/userspace/userspace_handler.c is a bare pass-through, and z_object_alloc() only range-checks otype — nothing bounds size. The stack-element branch is additionally reachable through the k_thread_stack_alloc() syscall via kernel/dynamic.c. Because subsequent kernel-object validation checks only the object's type and initialization state, the undersized handle passes K_SYSCALL_OBJ_INIT()/K_SYSCALL_OBJ_NEVER_INIT(), and the matching init syscall (for example k_mutex_init(), k_sem_init(), or k_thread_create()) then writes a complete object over the truncated allocation.\n\nAn unprivileged user-mode thread can therefore trigger a supervisor-mode out-of-bounds write into the kernel resource-pool heap, of a size and content it substantially controls, corrupting sys_heap chunk metadata and adjacent kernel objects. Under CONFIG_GEN_PRIV_STACKS the thread-stack branch additionally stores an attacker-influenced wild pointer as a user thread's privileged stack base. The practical result is escape from the CONFIG_USERSPACE sandbox — kernel-level code execution or at minimum kernel memory corruption and system compromise.\n\nExploitation requires CONFIG_USERSPACE together with CONFIG_DYNAMIC_OBJECTS (also selected by CONFIG_DYNAMIC_THREAD under userspace), and a calling thread with an assigned resource pool. The fix rejects both overflowing computations and frees the partially built descriptor."}],"affected":[{"vendor":"zephyrproject","product":"zephyr","collectionURL":"https://github.com/zephyrproject-rtos/zephyr","packageName":"zephyr","defaultStatus":"unaffected","programFiles":["kernel/userspace/userspace.c"],"programRoutines":[{"name":"dynamic_object_create"},{"name":"z_impl_k_object_alloc_size"},{"name":"z_impl_k_thread_stack_alloc"}],"versions":[{"version":"3.5.0","status":"affected","versionType":"semver","lessThanOrEqual":"4.4.2"}]}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/85c1c4c21945d9b8fcef03216f1ccb2b27794e3d","name":"Fix commit","tags":["patch"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-fg8c-9fhq-q7hv","name":"GHSA-fg8c-9fhq-q7hv"}],"metrics":[{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"}}],"problemTypes":[{"descriptions":[{"lang":"en","description":"integer-overflow","cweId":"CWE-190","type":"CWE"}]}],"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-09T17:54:39.210506Z","id":"CVE-2026-19569","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-09T17:55:18.376Z"}}]}}